Radiation Safety Management for the Decommissioning of Nuclear Facility

1. 2004 the Sino-Japanese Modern Engineering and Technology Symposium 19th October 2004, Taiwan Radiation Safety Management for the Decommissioning of Nuclear Facility October, 2004 TheJapan Atomic Power Co.

2. National Policy/Regulation

3. Basic Policy on Decommissioning Nuclear power plants should be decommissioned when the time comes at the responsibility of their operators Under the basic principle of securing safety and gaining the local community’s understanding and support The land will serve as sites for nuclear power generation again with the local community’s understanding. * The Long-Term Program for R&D and Utilization of Nuclear Energy (Japan Atomic Energy Commission, Nov. 24, 2000)

4. The Japanese standard process for the Decommissioning of nuclear power plants Recommended Standard decommissioning process Defueling PrimarySystem Decontamination (for LWR only) (about 5-10 years) Safe Store Dismantling Waste Disposal Land Reuse

5. Discussions on the standard process The short term forthe safe store would be beneficial for the future reuse of the site After 5 to 10 years safe store, the exposure dose of decommissioning workers could be reduced to thesame level with operation stage. Itwould not be acceptable to the local communitiesthat a closed nuclear power plant remains for long years. The availability of the operating plant work force that is highly knowledgeable about the facility.

6. About 5 to 10 years safe store Reduce radiation exposure during dismantling works Radioactive waste amounts Decommissioning costs Re-use of the site Public acceptance

7. Consideration Items for Case Study Decay of Radioactivity ① Decreasing Dose ② Decreasing Waste Volume • Reduction Remote Dismantling • Reduction Shielding Object • Reduction Disposal Waste • Reduction Dismantling &Treatment Work Extension over long period of time ③ Maintenance and Surveillance ④ Equipment Replace and Rearrangement ⑤ Reactor Dismantling is Delayed • Construction of Safe-store structures • Administration during Safe-store Period • Equipment Replace during Safe-store Period • Reconstruction of Facilities after Long Term Safe-store • Discontinuity of Engineering • Common Use Facilities are not Available

8. Key Factors for Scenario Selection - decommissioning cost - workload balance - availability of experienced personnel - managerial risk - conformity with Japanese national policy and guides - promotion rule making activities and construction of disposal facility - public acceptance - site re-utilization

9. Regulatory Procedure • Under the law for the Regulations of Nuclear Source Material, Nuclear Fuel Material and Nuclear Reactors Notification ofReactor Dismantling (Article 38 of the law) Safety Regulations ; Power station safety rules ＆ Tech. Spec (Article 37 of the law)

10. Comparison safety strategy between operating phase and decommissioning phase Prevention of -Public exposure -Work exposure Safety strategy while operation Safety strategy while decommissioning 【Points while operation】 • Safety operation • Safety system maintenance 【Points while decommissioning】 • Radwaste management • Discharge management Continuous Operational control (24hr) Management of decommissioning work

11. Safety strategy for dismantling work Prevent radioactive discharge and reduce activity while all decommissioning term to ensure public and worker safety 《Plant status》 Unnecessary criticality control Unnecessary fuel cooling shutdown No spent fuel Statical and highly safety level Some parts of facilities and building are irradiated or contaminated after 32 years operation Radiation control and radwaste management are necessary

12. Radiation discharge prevention 　・Choose less activated dust and fluid production technology 　・Collect by high performance filter 　・Maintain existing walls and ventilation sys. and fluid waste treatment sys. 　・Survey discharged gas and fluid Dose rate reduction 　・Reduce activity by safe store (10years)(dose rate1/4) 　・Use existing shield wall as radiation shield or wall for contamination prevention 　・Use additional shield, clean house, potential ventilation sys 　・Manage worker’s exposure Accident prevention 　・Fire prevention (remove oil, use flameproof tool, fire alarm, fireplug) 　・Accident prevention (work at high place, harmful materials, electric shock)

13. Tokai-1Decommissioning project

14. Locationof Tokai-1 Tokai-1 130 km Northeast of Tokyo Tokyo ● ●

15. Outline of Tokai-1 Tokai-1 is the first commercial NPP in Japan Role : To demonstrate and develop NPP Reactor Type : Magnox Gas Cooled Reactor Capacity : 166 MWe Fuel : Natural Uranium Magnesium Cladding Fuel with Graphite Sleeve Moderator : Graphite Coolant : carbon dioxide Reactor vessel : Spherical, 18m diameter Steam Raising Unit : 4 Units Turbine Generator : 83 MWe × 2 Units

16. General Arrangement of Tokai-1 Ｒｘ／Ｂ Ｔ／Ｂ ＣＣＰ

17. Permanent Shutdown Reason Tokai-1 is the sole Magnox NPP in Japan Tokai-1 is the oldest NPP in Japan Unit cost became higher than LWRs Jun.1996 Formal announcement for closure Mar.1998 Permanent Shutdown May.1998-Mar.2001 Defueling Jun.2001The last shipment of Spent Fuel Oct.2001 Submitted the notification of decommissioning plan Dec.2001 Commenced Decommissioning work Chronology

18. Decommissioning strategy for Tokai-1 All facilities will be removed. After decommissioning, the land is to be reused for future nuclear power operation. Reactor structure will be dismantled after 10-year safe-store. Conventional components are removed during reactor safe-store to utilize human resources. Project program is divided into 3 phases because of long term project (17years).

19. Decommissioning strategy for Tokai-1 - Cont. In each phase,project plan should be submitted to the regulator and approved. Waste disposal facility will be constructed prior to reactor dismantling. If a disposal facility is not available, safe-store period is to be extended.

20. Decommissioning Project Schedule Second Phase Remove SRUs Safe-Store of Reactor Area Buildings Dismantling

21. Work area in each Phase ;Scope First Phase Second Phase Fuel handling building facility Charge machine Gas duct Charge face facility Turbine building facility SRU: steam raising unit Spent fuel cartridge cooling pond Reactor service building facility Third Phase Dismantling RPV & Biological-shield Dismantling buildings(non-radioactive parts) Reactor internals /Reactor vessel Biological shield wall *Underground and basement are out of scope

22. First phase；5 years 3 2 1 3 3 3 1.Isolate reactor structure for safe store by valve out and plugging. 2.Drain and cleanup spent fuel cooling pond. 3.Remove components in turbine and reactor auxiliary buildings, including the fuel charge and discharge machines.

23. Second phase：5years 1 2 1.Remove 4 SRUs 2.Install Radwaste System

24. Third phase (first step):5years 2 1 1 3 Reactor structure is to be dismantled by remote operation manipulators. 1.Withdraw reactor inserts and take out graphite blocks 2.Dismantle RPV and Internals 3.Remove activated concrete shielding structures

25. Third phase(2nd step)：2 years 1 1 1 2 • After final survey, demolish all building structures besides basements and underground structures. • Finally, adjust the land on ground level.

26. First Phase Schedule

27. Turbine Building Equipment Removal

28. Removal of Turbine building equipment • 〔Period〕 April 2003 - March 2004 • 〔Outline〕 • Removal of Turbine generator • Removal of equipment in Turbine building • (Base for turbine, Condenser, Piping) • Removal of equipment in yard • (Switch yard, Oil Tank, Cooling water pump, etc) • Removal of toxic material • (Asbestos)

29. Removal of Turbine building equipment(Before removal)

30. Turbine Removal Removal of low pressure turbine rotor (26t) Removal of low pressure turbine lower casing (20t)

31. After removal of Turbine generator

32. Removal of Concrete Pedestal

33. Removal of Condenser

34. Removal of Turbine building equipment（After removal）

35. Feed Water Treatment Building Before After

36. Removal of Switch yard Before After

37. Before Removal of Pipe Bridge After

38. Recycle of Removed Material Recycle Metal Treatment (Segment& Melting) Product Concrete Crush into under 40mm Gravel for Landfill Toxic (Asbestos) Melting Material for Roadbed

39. Recycle of Removed Material (Turbine Removal Result)

40. Radioactive Waste

42. Radwaste treatment/disposal All radwaste arising from decommissioning are categorized into LLW. Radwaste are treated (decontamination, melting, burning, compaction, etc), solidified and packaged in containers, Eventually are disposed of at burial facility. Disposal facility will be constructed prior to 3rd phase. Radwaste arising in 1st & 2nd phase will be temporally stored.

43. Estimated waste amounts Unit:kilo ton

44. Radioactive level Level Ⅰ Level Ⅱ Level Ⅲ Hot Gas Duct Under clearance Ⅳ Charge Machine Secondary biological Shield floor Primary biological Shield floor Primary biological Shield wall RPV Secondary biological Shield wall Cold gas duct

45. Upper Limit of Radiation Control

46. Strategy on Waste Disposal Facility L1 L2 L3 Artificial barrier 50-100m underground Restricted period: 300years Concrete pit Near surface Restricted period: 300years Without concrete pit Near surface Restricted period: 30-50 years The facility is to be constructed for all Japanese power company at Rokkasho Site The facility is to be constructed for Tokai-1 decommissioning at Tokai site

47. Location of Disposal Site Rokkasho Site for L1, L2 waste ● Tokai Site for L3 waste Tokyo ● ●

48. JNFL L2 waste disposal center L2 Waste Disposal Facility

49. Ground surface Cover soil Bentonite/sand mixture Concrete pit Drum Porous concrete layer Inspection tunnel Cement base backfill Drain pipe Bedrock Bedrock L2 Waste Disposal Facility Concept of L2 waste disposal facility (Concrete pit) JNFL L2 waste disposal center Placing reinforced concrete lid Waste emplacement in disposal facility

50. L1 Waste Disposal Facility Access tunnel about 100m Test cavern about 400m Connecting tunnel about 900m Disposal Cave Main tunnel